I personnally think that the MSI P35 Neo2 is a very good board if you're only going for a single card setup. It has some very nice cooling and good features. If you want to go SLI, then either get the 680i, the 750i or the 780i. The 780i supports 3-way SLI and PCI-E 2.0. The 750i has PCI-E 2.0. and the 680i is basically just a 780i without 3-way SLI and PCI-E 2.0. The prices on the 680i are very good ATM so maybe have a look at one of them if you want to go SLI. For Crossfire, the X38 is the only Intel option. The P35 can't do 2x 16 lanes.
Oh Yess! Worshipme has made it very clear that C2D is much better than QC
I wouldn't say it's much better, but you can buy a C2D E8xxx for less than a Q6600 and get slightly better performance in games. With the money saved from choosing the dual, a better graphics card could be bought, which would make a much bigger difference.